At least 13 persons were arrested by US Federal agents in a sting operation and charged with conspiring to provide material support and resources to Sri Lanka's LTTE rebels, which are on State Department's terrorist list.
Most of the arrested were Canadian or Sri Lankan nationals. Additional arrests were expected, sources said.
Described as supporters of LTTE, some of them were charged with trying to buy sophisticated weapons, including surface-to-air missiles from a black market, for the group's use in the ongoing fight with the Sri Lankan Government.
They were allegedly trying to buy 10 Russian made missiles and 500 AK-47 rifles.
The 54-year-old India-born Nachimuthu Socrates, who was being held pending court appearance later this week, was alleged to have tried to bribe a State Department official who was actually an undercover agent to get LTTE removed from list of foreign terrorist organisations and obtain classified information.
Assistant US Attorney Mark Rubino said the government viewed Socrates as a flight risk and sought his detention.
Just unsealed court documents allege that those arrested sought to procure military equipment, communications and indulged in a "myriad" of other criminal activity. But their target was not the United States, officials said.
Socrates is also alleged to have sought to bribe to get a classified document about US investigation into Tamil Rehabilitation Organization, charity suspected of being front organization for LTTE fundraising.